1. The Christchurch earthquake, New Zealand 2011
Case study of a tectonic event.
The Christchurch earthquake, New Zealand 2011
Aim: to describe the location, causes and impacts of the New Zealand earthquake
Challenge: To evaluate the extent to which technological developments can have a positive impact on mitigation.

2. The Christchurch earthquake, New Zealand.
Task: Complete the ‘fact file’ about the Christchurch earthquake.
On 22nd February 2011, at 12.50pm, a slip along the boundary between the Australian and Pacific plates caused at earthquake with a magnitude of 6.3 on the Richter scale. The epicenter of the earthquake was close to the city of Christchurch. The quake lasted for 10 seconds. It caused considerable damage, 181 deaths and 2000 injuries.

3. Describe the location of Christchurch, New Zealand.
Where is NZ in the world? Where in relation to other countries? Where is Christchurch? Use compass directions.

4. News clip: https://www.youtube.com/watch?v=eAmzE_yvNZ8
Video clip: What are some of the problems shown?

5. How it happened Christchurch
The earthquake occurred on a conservative plate margin where the Pacific Plate slid past the Australian Plate in the opposite direction.  It was technically an aftershock from a larger earthquake in 2010 but the impacts were more severe.
Christchurch

6. The cause of the earthquake.
The earthquake occurred on a conservative plate margin where the Pacific Plate slid past the Australian Plate in the opposite direction. 
Stress builds up over time. This was suddenly released. The focus was quite shallow. Seismic waves (shock waves) radiate from the focus. The epicentre of the earthquake was just 10km from the city of Christchurch.

7. Primary effects
Ground shaking The ground was violently shaken and rose by up to 1 metre in places. Liquefaction The ground shaking caused water to rise to the surface. This made the ground very soft and everything from buildings to roads, cars and trees sunk. Landslides. Significant landslides and rock falls in the southern part of Christchurch were reported. Tsunami: There was a 3.5m tsunami wave in Tasman Lake, following the quake-triggered glacier breaking off from Tasman Glacier.

8. Secondary effects Building failure
Many were destroyed by the 2011 earthquake.
All types of buildings were affected, even some modern earthquake-proof buildings.
Fire
A collapsed building in Christchurch had to be extinguished in order to recue people trapped inside.
Water shortage/contamination
Water & sewage pipes were ruptured during the quake and this allowed them to mix and contaminate the water.
As a result, lots of bottled water had to be supplied.
Housing
Thousands of people had to move out of their homes as it was unsafe for them to stay as their homes may have been weakened and could collapse in an aftershock.
There were no reports of famine or disease

9. Environmental impacts
Economic impacts
Social impacts
Costs of repairs to infrastructure
$40billion worth of damage to the infrastructure
Insurance costs - increased
Losses to business and employment
Christchurch could no longer host Rugby World Cup matches so lost the benefits of its income. The tourism industry also suffered as a result.
The number of guests to hotels in Christchurch fell by over 75%
181 people were killed and around 2,000 people were injured
Impact on schools. The earthquake closed many schools temporarily. 19 schools suffered major damage.  
Many people moved out of the city.
Environmental impacts
Sewage pipes were broken and contaminated water supplies.
Liquefaction caused some flooding and cars to fall into sink holes.
Icebergs broke off from the Tasman glacier

10. Managing the earthquake hazard. New Zealand is an Advanced Country (AC). It has invested in technological developments to mitigate earthquake hazards. Earthquake resistant buildings. All buildings are designed to ensure that they will not collapse in case of an earthquake. Old buildings have been retrofitted to withstand future earthquakes. Seismic monitoring systems. Monitors and computer systems are used to detect minor earth movements. This can provide emergency services with information within a few minutes of an earthquake. GIS mapping of seismic activity. By mapping high risk areas, local plans can be produced to ensure no homes are built in seismically dangerous zones. Education and community preparedness. In New Zealand regular earthquake drills are carried out to ensure people know what to do. Emergency services. New Zealand has very well equipped emergency services. e.g. St John’s ambulance had 16 ambulances operational within half an hour of the quake. Insurance. $898 million was paid in building claims. This helps businesses and individuals to recover from the earthquake quickly.

11. This is Sky Tower in Auckland, New Zealand.
Sky Tower is the tallest tower (328 metres) in the Southern Hemisphere. Auckland is in an earthquake zone and so the tower is constructed from a high strength, high performance concrete. Sky Tower's foundations go down more than 15 metres.

12. Magnitude - 7.1 Richter scale Time – 4.35am
A mystery: New Zealand had experienced a stronger earthquake 5 months earlier but it killed fewer people!
Study the information below. Can you suggest reasons why the weaker, second earthquake killed more people?
Earthquake 1.
Date – 4 September 2010.
Magnitude Richter scale
Time – 4.35am
Epicentre – 40km from Christchurch
Focus – 10km depth
Duration – 40 seconds
Deaths – none
Injuries – 2 people
Earthquake 2.
Date – 22 February 2011.
Magnitude – 6.3 Richter scale
Time – 12.51pm
Epicentre – 10km from Christchurch
Focus –5km depth
Duration – 10 seconds
Deaths – 181
Injuries – 2000 people

13. The second earthquake, in 2011, killed more people because –
It occurred in the middle of the day, (12.51pm) when the city centre was very busy with workers and shoppers.
The previous earthquake had weakened buildings, making them more likely to collapse.
The focus of the 2nd earthquakes was closer to the surface, making the shaking stronger.

14. Question: For a named example, evaluate the success of technological developments in mitigating the impacts of a tectonic hazard.
What example?
What technological developments have been used?
How powerful was the earthquake? Signs of success - i.e. limited death toll? Destruction?
On the other hand –
Over 180 people still died & 2000 injured.
Some buildings still collapsed.
Can earthquake impacts be totally avoided? Why not?